Mzungu

I have an issue with a few push rod tubes. 2 of 8 intake push rod tubes (cylinder 1 and 3) have been eaten up by the stock guide plates. The damaged tubes are perfectly straight and are 3/8 "

This is a fresh 427 build. I am running a Comp hydraulic roller assembly with stock oval port heads. Also I have 1.72 roller tip rockers.

Everything I have read indicates that this could be a push rod hardness issue, a geometry or a guide plate issue.

Anyone else run into this issue?

v2racing

You need to run hardened pushrods with guide plates. Your's appear to not be hardened.

Now you need to worry about how much damage the rest of the engine has gotten from all the metal shavings off the pushrods!

PAmotorman

some BBC after market push rods only have a hardened insert on one end to ride in the push rod guide and if installed upside down they will wear like yours. just change your oil and filter after correcting your push rod problem and you will be fine

Mzungu

Thanks. I will get hardened push rods, flush the oil and change the filter.

Does anyone think it might be a geometry or stock guide alignment issue?

gkull

Guide plates should never touch the push rod............... that means period. If you have 3/8th push rods you should have a few thousands gap around the rod when you install the guides. Over the years I have had to die grind guide plates for clearance when assembling motors for clients and even my own.


So when you are assembling the head you put the studs on the guide plates minor tight with the ability to stills tap the guide plates around with locktight blue or a hard dry sealant like permatex on the stud threads. I mean with a small ball peen hammer and round punch.

You set the valve lash and hand turn over the motor several times watching for any push rod rubbing and tap the guides for equal clearance and then turn the rocker studs down that final 1/8 or 1/4 turn to lock them in place and let dry before firing.

Looking at your picture you must have 7/16th guide plates or something to ware that much off your 3/8th push rods

bashcraft

If that were the case, you wouldn't need guide plates.

But yeah, you need to move them around and get the pushrod centered in the slot.

502 C-3

As gkull stated, I have also ground the guide plates for pushrod clearance. No ill effects on a 468 with a solid lifter ultradyne cam.

gkull

Early in my traveling racing mechanic carrier I thought that guide plates were about worthless. So I asked someone to explain why. What you don't see unless you dig up some you tube video on valve spring surg and uncontrolled harmonics. The terrific Bending forces on the push rods. At that point the guides keep the rod in the rockers.

So my statement is true. You never want to have the guide touch the push rods

StraubTech

That pushrod did not get heat treated, or Chinese import stuff. Also welded ball is good for OEM type valve train. If this engine has seen up grades then a good 1 piece swedged end pushrod is best.

bashcraft

I'm not sure what this means.

Of course you don't want them to touch, but they will. What do you think keeps the rocker arm from swinging around off of the valve?

Mzungu

14 of the other push rod tubes are fine (so far). Once I get the new hardened tubes I will fit all of them and more than likely grind down the any guide plates that I cannot get a few thousands feeler gauge into. I will say that most of the tubes are fairly snug in the guide plates and have some movement. I believe as others have already mentioned that the main issue is that the tubes are cheap, not hardened or part of a bad batch...

Thanks everyone for all the input.

caryb78

I had the same problem. On mine the push rod end actually got pushed down into the tube which made the tube fatter and rubbed the guide plate. This was on 4 rods. Changed rods flushed oil system, changed oil every 50 mile 3 times, put magnets on filter. all ok.